Kick off the SDK based on Symfony's MCP SDK

src/Capability/ResourceChain.php

@@ -0,0 +1,77 @@
+<?php
+
+/*
+ * This file is part of the official PHP MCP SDK.
+ *
+ * A collaboration between Symfony and the PHP Foundation.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Mcp\Capability;
+
+use Mcp\Capability\Resource\CollectionInterface;
+use Mcp\Capability\Resource\IdentifierInterface;
+use Mcp\Capability\Resource\MetadataInterface;
+use Mcp\Capability\Resource\ResourceRead;
+use Mcp\Capability\Resource\ResourceReaderInterface;
+use Mcp\Capability\Resource\ResourceReadResult;
+use Mcp\Exception\InvalidCursorException;
+use Mcp\Exception\ResourceNotFoundException;
+use Mcp\Exception\ResourceReadException;
+
+/**
+ * A collection of resources. All resources need to implement IdentifierInterface.
+ *
+ * @author Tobias Nyholm <tobias.nyholm@gmail.com>
+ */
+class ResourceChain implements CollectionInterface, ResourceReaderInterface
+{
+    public function __construct(
+        /**
+         * @var IdentifierInterface[]
+         */
+        private readonly array $items,
+    ) {
+    }
+
+    public function getMetadata(int $count, ?string $lastIdentifier = null): iterable
+    {
+        $found = null === $lastIdentifier;
+        foreach ($this->items as $item) {
+            if (!$item instanceof MetadataInterface) {
+                continue;
+            }
+
+            if (false === $found) {
+                $found = $item->getUri() === $lastIdentifier;
+                continue;
+            }
+
+            yield $item;
+            if (--$count <= 0) {
+                break;
+            }
+        }
+
+        if (!$found) {
+            throw new InvalidCursorException($lastIdentifier);
+        }
+    }
+
+    public function read(ResourceRead $input): ResourceReadResult
+    {
+        foreach ($this->items as $item) {
+            if ($item instanceof ResourceReaderInterface && $input->uri === $item->getUri()) {
+                try {
+                    return $item->read($input);
+                } catch (\Throwable $e) {
+                    throw new ResourceReadException($input, $e);
+                }
+            }
+        }
+
+        throw new ResourceNotFoundException($input);
+    }
+}